1. Field of the Invention
The present invention relates to a hydraulic pressure propelled device for carrying out measurements and interventions during injection or production in a deflected well.
By the expression "deflected well" is meant here not only wells which are slightly deflected but also those which are greatly deflected and which require pumping of the equipment to reach the production zone.
The invention is more especially applicable for carrying out measurements, for example of pressure and flow rate, at the level of geological formations or any other intervention in a well when it is a question of revealing the flow pattern of the productive part of a deflected blowout well. Such measuring techniques are well known by specialists and will not be described in greater detail here.
The measuring or intervention instrument may for example be a well-logging probe. It may be connected electrically to the surface by a well-logging cable, or it may not be connected to the surface, comprising in this case a self-contained power supply and a memory for storing the data.
2. Description of the Prior Art.
It is already known from U.S. Pat. No. 4,349,072 to lower, at the end of a cable into the vertical and deflected part of a well, a probe fixed to the lower end of an extension which may reach a length at most equal to the length of the drain (for example about 500 to 1300 m). In its upper part the extension is connected to a propulsion system generally called a "locomotive", formed of cups whose rubber lining provides substantially total sealing with the inner walls of the tubing. This locomotive is itself attached to the cable.
When the weight of the assembly is not sufficient for lowering the equipment into the pressurized well, the volume situated above the locomotive is pressurized by pumping, so as to push the equipment (probe and extension) into the deflected zone which interests the producer. The measurements are made during the pushing phase when the probe is in the production zone, or during the rising phase. These measurements may be advantageously repeated.
Because of the seal provided by the linings, it is not possible for the fluid to flow freely and rise to the surface. Under these conditions, flow rate measurements, for example, in a well under production become impossible, unless a second tubing is used and is reversed for the rising fluid, but this solution is costly and must be provided during equiping of the well, for the operation of lowering two tubings must be simultaneous.
Moreover, the whole of the equipment (probe, extension and locomotive) is raised by pulling on the cable. If the production tubing has a substantially constant diameter and since the linings provide good sealing, a decompression phenomenon may be observed and so aspiration of the fluid, likely to create pressure imbalances, and fluid displacements leading to uncontrolled starting up of production.
It is known more particularly from French Pats. Nos. A-2,473,652 and 2,500,419 to move a probe in a well by means of a liquid fluid pumped from the bottom of the well, passing through the pumping means and flowing through at least one aperture situated above an automatically controlled inflatable sleeve. The fluid will exert a pressure on the sleeve which will therefore advance into the well.
Devices are also known, as described in the U.S. Pat. No. 3,070,167, which comprises members having springs which are expanded or compressed so that these members provide sealing with the tubing and may allow the extension to be pumped into the well.
U.S. Pat. No. 2,122,697 also mentions a sensor lowered by circulation through pumping and which is then anchored at the bottom of the well by means of a deformable membrane and springs; whereas the U.S. Pat. No. 3,104,714 relates to a pumped tool having an electric cable and which comprises shoes which will brake and prevent the tool from rising.
Numerous problems appear in production well-logging when it is a question of the production of blow-out wells, i.e. wells under pressure. There is a problem first of all in introducing the assembly of the tools into a pressurized well.
It is also known to use an air lock (generally having a length of 10 meters or so), at the surface, for lowering and raising in a pressurized deflection well a welllogging probe and an extension, element by element. Each operation requires more especially a series of valve manipulations, pressurizing and drain operations which are long and tiresome, to the extent that an extension must be assembled for reaching 300 to 500 meters for example.
It is also known to lower a probe and an extension into a pressurized well by snubbing in which each of the elements of the tubing, after being screwed, is forcibly moved from the surface by a hydraulic cylinder. They may be also introduced by coil tubing in which the continuous tubing is wound on a large drum and is driven into the pressurized well by rollers disposed at the surface. Such equipment is heavy and costly, even fairly fragile, more especially the coil tubing.
Finally, it is quite possible to meet variations of diameter in the production tubing during the advance of the well-logging equipment.